I've overdosed my beers on Campden Tablets

[bigken462]

For the last 6 batches of beer, two of which I made back in November that I consider undrinkable - but I think for other reasons, and I fear 4 recent batches that's not yet finished I've been mistakenly overdosing them on Campden Tabs

For some time now, I've often wondered why the directions on the bag said to treat the water with 1 tablet per 1 gallon of water when most on the forum uses 1 tab/20gal. This was a question I had been meaning to ask my LHBS about for several months, but I had always forgotten until today. I simply thought they were using a lesser strength of it than what most people here were using. It turns out, this was supposed to be intended for wine makers.

So, all that said, what detrimental effects do ya'll think I will have by using a dose that I did of 1 tab/gal? This was always either pre-boiled or heated to sparging temps.

I just have a sickening feeling in my stomach I've just messed up 4 recent batches of beer that I've been making for a large event this summer.

2 of the 6 seemed to ferment out fine. My last one is not doing so well, but I think I can chalk it up to the yeast sitting in shipment from NB for over a week and me choosing on a last minute push to do a 3rd brew and not using a starter.

So now that I know, what do you think the effects will be?

 

[slym2none]

I believe the effects happen immediately, and then the chemical dissipates/evaporates out.

WAG here, but I am thinking you only wasted Campden tabs, and that's the only detriment.

This totally might be my ultracrepidinarism talking, though.

 

[pvpeacock]

I believe that Campden tablets are used in wine making as a preservative and are used at that level (1 tablet per gallon). For beer making, I use it to get rid of the chloramine in my tap water and use 1/2 tablet per 5 gallons of water. I don't know what affect it will have on the taste of your beer, but if they use it at those levels for wine, I can't imagine it would have that big of an affect on your beer, but I could be wrong.

 

[slym2none]

@Yooper for a definitive answer to this...

 

[Yooper]

@Yooper for a definitive answer to this...

I have no real idea! My gut tells me that the boil will "off gas" the sulfites, but I really have no honest clue.

 

[bigken462]

Time will tell I guess. I take blame for this myself, but I sure wished my LHBS would have added a extra line on the instructions for beer makers that one tablet would do for treating 20 gallons. I'll chalk this up for experience and lessons learned.

 

[ajdelange]

The stuff of Campden tablets is often referred to a 'solid sulfur dioxide' and for example, potassium metabisulfite with water gives
K2S2O5 + 3 H2O ---> 2H2SO3 + 2K+ 2OH-

There really is no such thing as H2SO3 (sulfurous) acid but one can think of it as sulfur dioxide dissolved in water.

H2SO3 = H2O + SO2 <----> HSO3- + H+ <---> SO3-- + 2H+
................................pH=1.9......................pH=7.2

Think of the two pH values as being markers on a continuous pH scale. A solution of metabite contains three species: SO2, HSO3- and SO3--. The farther to the right the more SO3-,the farther to the left the more SO2. At pH 1.9 there are equal amounts of SO2 and HSO3-; at pH 8.2 there are equal amounts of HSO3- and SO3--. In between, i.e. at mash and kettle pH HS03- predominates. To boil off the SO2 one would have to be at pH appreciably below 1.9. To demonstrate put a drop of strong acid on a Campden tablet. It will fizz (do this outside and stand back - SO2 is a choker for sure).

So the mash and kettle aren't going to boil it off. But HSO3- is a strong reducing agent (that's why we use it to get chloramine and chlorine out). So if there is enough stuff in oxidized state in the wort the bisulfite should get it converting to Sulfate e.g.

RCOOH + HSO3- --> RCHO + SO4-- + H+

This is what I would hope would happen to the bisulfite. Indeed some brewers add metabite to their worts in the hopes of keeping them in reduced state. The question is as to how much will be oxidixed (to sulfate). That suggests the following additional example of reduction by bisulfite

H2O2 + HSO3- ---> SO4-- + H2O + H+

and implies that the answer to the original question is that OP could have oxidized the bisulfite to sulfate with readily available hydrogen peroxide. I just wouldn't be comfortable dumping hydrogen peroxide into my mash, kettle or beer so I think the thing to do is hope that there were enough oxidizing agents in the wort to take care of things.

The risks with unconverted bisulfite are with respect to yeast health. Vintners use it to biologically stabilize must which means it is not good for yeast (or bacteria). The fact that wine does ferment suggest that it is harder on bacteria than on yeast so perhaps we need not worry about this aspect of it.

 

[bigken462]

Somewhere very deep down in my stash of old college books, I recall hiding those that contained that language above. Reminds me of learning the acid base balance in college and poking my eyes out with the pen.

Who would have thought learning that stuff would some day be useful. lol

I will have to take your word for it. But in a month or two, I'll dig up this old thread and post some feedback of what it tastes like.

 

[bigdaddybrew]

I've used campden tablets to treat the juice when making fruit wine at similar levels you are describing to prevent the wild yeast from fermenting. After 24 hrs I added my intended yeast. Packaged wine yeast is usually sulfite resistant not sure about beer yeast. The fact that your beer is fermenting is a good sign. How will it affect the flavor? Time will tell but my wine never tasted like campden tablets.

 

[IslandLizard]

Thank you @ajdelange for the thorough chemical explanation and how pH plays a role which components are present and active at a given pH level.

For the users, remember you can "treat" 2 different ways with meta:

1. As a preservative in fruit juice, wine, cider, etc. killing present microbes and wild yeast. Dosage 1 tablet per gallon (min. 150ppm free SO2)
2. As an agent to remove Chlorine and Chloramines from water. Dosage 1 tablet per 20 gallons (~7 ppm SO2)

 

[orangehero]

Any thoughts on using KMeta as an antioxidant during packaging beer? For example using a solution as the sanitizer.

 

[ajdelange]

Beer actually contains quite a bit of bisulfite on its own. You may have noticed, particularly with lager strains, the aroma of SO2 wafting through the room with the fermenter. Some brewers add more but you have to be very careful. Bisulfite, you'd think, would be great because it should, for example, be able to reduce diacetyl to acetoin and it can but it also forms adducts which taste worse than the diacetyl. So if want to experiment go very slowly.

I spotted an interesting comment in HBS&Y to the effect that while HSO3- is a great reducing agent yeast are even better and can reduce bisulfite all the way down to sulfide. Not a very pleasant prospect that!